Auxiliary spring for a tubular magazine



Jan. 19, 1965 H. A. INTO AUXILIARY SPRING FOR A TUBULAR MAGAZINE 2 Sheets-Sheet 1 Filed Sept. 25, 1963 Q3 EOR DM FQQ o O RT Y mm N mN M v d N] R W W m N T -Q 9 1V! W A m -QE W W I. -3 w E -3 3 H m AW -Q m 6w -ww I A. A A g; fi -M A l II \IIIIIIIAHVIIIIIER\Z IIIM I .l 7 u m i V m. w I N \iiili4l! I U4I Hlli lllll11 llll'lk A O- m 4N N Jan. 19, 1965 H. A. INTO 3,165,852

AUXILIARY SPRING FOR A TUBULAR MAGAZINE Filed Spt. 25, 1963 2 Sheets-Sheet 2 FIG-2 INVENTOR HENRY A. INTO A T TORNE Y United States Patent 3,155,852 AUXELIARY SPRING FUR A TUBULAR MAGAZINE Henry A. Into, Waiiingford, Conan, assignor to Olin Mathieson Chemical Corporation, a corporation of Virginia Fiied Sept. 25, 1963, Ser. No. 311,366 6 Ciaims. (Cl. 4249) This invention relates to an improved magazine spring arrangement for firearms having a tubular magazine whichis provided with a follower and spring.

This invention more specifically relates to an improved magazine spring arrangement for a firearm having a tubular magazine. The spring arrangement includes an auxiliary spring which functions to reduce the magnitude of movement of the shells during recoil and to shorten the time required to overcome the inertia of the shells and return them to the correct feeding position in the magazine.

Timing is an extremely critical factor wihch must be controlled in feeding shells from a tubular magazine into the receiver of a self-loading firearm. In firearms wherein the feeding of shells is regulated by a pair of cutoffs mounted on opposite sides of the mouth of the magazine such as disclosed in my copending application, Serial No. 240,586 filed November 28, 1962; the time allowed for feeding the shells from the magazine into the receiver is approximately 15 thousandths of a second.

The problems recognized and overcome by this invention can be summarized as follows:

When a gun is fired, the shells in the magazine tend to remain stationary due to their inertia while the .gun itself moves rearwardly in recoil. During recoil, the shells in the magazine compress the magazine spring as the mouth of the magazine moves away from the shells. The amount by which the magazine spring is compressed will depend on the spring force acting on the shells during recoil and the available space in the magazine for movement. These factors directly affect the distance the mouth of the magazine will move away from the rearmost shell and therefore the distance the shells must be moved relative to the magazine to be in proper feeding position adjacent the cutoffs.

There is a recognized variation in the overall length of shotshells of the same gauge which amounts to approximately one quarter inch, depending on type of closure, loading, and manufacturer. In a two-shot magazine, this can result in a column length variations of onehalf inch or more. In addition, some slight clearance must be allowed over the length of the two longest shells which can be inserted into the magazine. Therefore, the magazine must be long enough to accommodate the long est shells with some slight clearance. When shorter shells are used, the space in the magazine available for shell movement during recoil is increased by the difference in length between the shorter shell and the longest shell available. Shorter shells are therefore free to move farther from the mouth of the magazine than longer shells.

, These variables are the different distances of travel of the various types of shellsthat can be used, and the inertia 3,lii5,852 Patented Jan. 19., 1965 ice which must be overcome so that the shells can be moved toward the mouth of the magazine.

With the conventional single magazine spring as commonly employed in tubular magazines; the force exerted by the magazine spring on two shells is not double the force exerted on one shell even though the spring is compressed from its original position twice as much when two shells are in the magazine as when only a single shell is in the magazine. The result is that the time required for two shells to return to the mouth of the magazine afiter recoil will be greater than for a single shell unless an added tome can be applied to the shells to overcome the doubled inertia forces.

In order to obtain the added force necessary to limit the time required to return the shells to the mouth of the magazine when there is more than one shell in the magazine; I employ an auxiliary spring in the magazine tube. The auxiliary spring is arranged so that it is operative only when two shells are'in the magazine to provide the force necessary to overcome the increased inertia of the shells.

This invention will now be described in detail below with reference to the accompanying drawings in which:

FIGURE 1 is a sectional cut-away view showing the novel arrangement of elements according to my invention when two or more shells are positioned in the magazine.

FIGURE 2 is a view similar to FIGURE 1 showing the arrangement of elements when there is only a single shell in the magazine.

FIGURE 3 is a graph illustrating the spring forces applied to cartridges in accordance with this invention.

Referring now to the drawings, FIGURE 1 shows a cut-away view of a tubular magazine generally indicated 1 which is connected at one end to the receiver 2 of a firearm. A magazine follower 3 and a magazine spring 4 are mounted in the magazine. A divider 5 is mounted in magazine 1 and separates the magazine into a cartridge receiving chamber 6 land a gas piston chamber 7. The gas piston chamber houses a gas piston (not shown) which functions in a semi-automatic firearm to operate one or more slide arms 8 and 9 as disclosed in copending US. patent application, Serial No. 202,510 filed June 14, 1962. Shells 10 and 11 are inserted into the magazine 1 through an opening 2A in the bottom'of the receiver and compress magazine spring 4 as follower 3 moves forward.

A pair of cutofis 12 and 13 (or other suitable means) hold the shells in position in the magazine and selective ly feed the shells into the receiver as disclosed in my said copending applioatiomserial No. 240,586. V The improvement according to this invention comprises an auxiliary spring 14 which is preferably attached to the follower 3. Alternatively auxiliary spring 14 may be secured to divider 5 or looselypositioned in the magazine between follower 3 and divider 5. An end coil'lS of auxiliary spring 14 is interlocked in an annular recess 16 formed in the interior of follower 3. Auxiliary spring 14 moves with the follower and is inoperative unless there are two shells in the magazine. By this arrangement, the shooter will need to exert only the normal amount of force to insert the first shell into the magazine. Note in FIGURE 2 that when only one shell is inserted, the auxiliary springis' inoperative and the shooter need only compress magazine spring 4 in the usual manner to load the shell. .It is only after the second shell has been in serted partially into the magazine that auxiliary spring 14 engages the divider 5 and begins to exert a force in opposition to the loading of a shell. This added force is exerted only during the insertion of the last portion of the second shell and is not readily noticeable to the shooter and therefore not a great inconvenience.

The function of auxiliary spring 14 is to provide the extra force necessary to overcome the doubled inertia forces present when two shells are in the magazine.

During recoil, the shells and 11 as seen in FIGURE 1 remain stationary while the gun moves rearwardly. The result is that the cutoffs 12 and 13 which selectively feed the shells into the receiver move away from the shells and the regular magazine spring 4 and auxiliary spring 14 are further compressed. Both springs 4 and 14 must exert enough force to overcome the inertia of the shells and start the shells moving rearwardly towards the cutoffs 12 and 13 if the shell 10 is to be properly fedinto the receiver in the split second that the cutoffs are actuated. Th e'auxiliary spring 14 performs two functions. It provides an extra spring force tokeep the mouth of the magazine from moving too far away from the shells,

thereby shortening the overall distance the shells can move. It also provides an increased spring force to over-.

come the inertia of the shells and start them moving toward the cutoffs. If there'is only a single shell in the magazine as shown in FIGURE 2, auxiliary spring 14 is inoperative and the regular magazine spring 4 provides adequate force to overcome the inertia of a single shell and move the shell quickly into engagement with the cutoffs after recoil. When two cartridges are inserted in the magazine as seen in FIGURE 1, the magazine spring 4 is compressed and deflectedtwice as much; however, the spring force exerted on the shells is not doubled. The inertia of the two shells; however, is double the inertiaof a single shell. Auxiliary spring 14 therefore functions to provide the'added force necessary to act against the doubled inertia forces and return shell10 of its feeding 'position against the cutoffs. ,Merely increasing the size;

or the weight, of the regular magazine spring 4, to provide the added force would create loading problems not found in my novel spring arrangement and would not provide the increased force only when necessary. I

FIGURE 3 graphically illustrates the principle of my invention bymeans of a diagram showing a spring force in pounds plotted against spring deflection measured in inches. I is .compressed by inserting shells into the magazine and the spring force increases as the spring is deflected. The solid linein the graph illustrates how spring force .in creases in a straight line as themagazine spring is de- Spring deflection occurs as the magazine spring flected. Point A shows the'defiection andthe force ex- 'erted by the conventional magazine spring after a'single cartridge is inserted in the magazine. Point-B shows the deflection and force exerted by the conventional magaizne spring after two cartridges have been inserted in the magazine The dotted line in the graph shows the increased force provided by the auxiliary spring mounted in the manner contemplated by my invention. Note that the auxlliary springbegins toact almost at the end of the deflection stroke and adds considerably tothe spring force'exerted against the two shells in the magazine.

A representative setof numerical values indicates that .With no shells in the magazine the conventional magazine spring has an initial load of approximately 8 pounds. When a single shell is inserted, the spring is' deflected approximately 2.5 inches and the spring force increases to about 11 pounds. This is the total force acting on a single shell and is adequate to overcome the inertia. of the shell and move the shell rearwardly after recoil. With the insertion of the second cartridge, there is an additional deflection of about 2.5 inchesfand the spring force exerted by the conventional magazine spring 'in-' occur when there are two cartridges in' the magazine.

accordance with the preferred embodiment illustrated While this invention has been described in detail in in the drawings; it is understood that certain variations and modifications are contemplated which are within the spiritand scope of the appended claims.

I claim: I l. Ina firearm including a receiver, a tubular magazine connected to said receiver'at one'end to receive a plurality:

of shells, a follower slidable in said magazine, a magazine spring mounted in 'said tubular magazine exerting a force.

to move said follower rearwardly toward the receiver; means exerting an additional force to move said follower onlywhen'at least two shells are positionedin said tubular magazine, said means being positioned in said magazine and being inoperative when less than twoshells are in said magazine. I a

, 2.'The firearm of claiml in which said means'is a coil spring having a substantially shorter overall expanded length than said magazine spring.

, 3. The firearm'of claim 2in which said means is fas tenedat oneend to said follower and is mounted concentrically relative to said magazine spring. 7

4. The'firearm of claim 3 in which said means is fas-.- tened'to' said follower-by interlocking an endcoil of said coil spring in an annular groove in saidfollower.

5. In ajfirearm, amagazine tube for receiving and holding a plurality of shells, a magazine spring normally urging said shells rearwardly. in said magazine tube, a follower positioned between saidmagazine spring and the adjacent shell, -means exerting an additional 'spring force on said shells only when there are at least two. shells in said magazine, saidumeans being1positioned in said magazine and being inoperative when, there are'less than two shells insaidmagazine. I

6. In a firearm, a receiver, a magazine tube for holding 1.1 plurality of cartridges'having one end opening into said receiver, adivider insaid magazine tube, a'magazine spring and afollower positioned in said magazine tube between said oneend and said divider, means-positioned adjacent said oneend for selectively feeding shells from .said magazine tube into saidreceiver, an opening in said 1 receiverfor insenting shells in said magazine thereby moving said follower forwardly and compressing said magazine spring, means exerting-an added springforce biasing said shells rearwardly, only when thereis more thanone shell in saidmagazine, said means beingposi- ,tioned in said magazinebetween saiddivider'and said follower. v

I I 5 References Cited'by the Examiner UNITED srATEsP TENTs I 1,061,787 5/ 13 Simpson 42 -49 2,645,873 7/53 Crittendon et a1. 4221 BENJAMIN A. BORCHELT, Primary Examiner. 

1. IN A FIREARM INCLUDING A RECEIVER, A TUBULAR MAGAZINE CONNECTED TO SAID RECEIVER AT ONE END TO RECEIVE A PLURALITY OF SHELLS, A FOLLOWER SLIDABLE IN SAID MAGAZINE, A MAGAZINE SPRING MOUNTED IN SAID TUBULAR MAGAZINE EXERTING A FORCE TO MOVE SAID FOLLOWER REARWARDLY TOWARD THE RECEIVER, MEANS EXERTING AN ADDITIONAL FORCE TO MOVE SAID FOLLOWER ONLY WHEN AT LEAST TWO SHEELS ARE POSITIONED IN SAID TUBULAR MAGAZINE, SAID MEANS BEING POSITIONED IN SAID MAGAZINE AND BEING INOPERATIVE WHEN LESS THAN TWO SHELLS ARE IN SAID MAGAZINE. 